Advances in polymerization and catalysts have produced new polymers having improved physical and mechanical properties useful in a wide variety of products and applications. Metallocene catalyst systems have been widely used to produce polyolefins and have provided a variety of new and improved polymers. Catalyst systems have also been used that comprise more than one catalyst component, which in effect provide more than one active site to polymerize monomers during the polymerization process, and can be used to produce multimodal polymers. However, there is continued focus in the industry on developing new and improved catalyst systems. For example, there has been a focus on improving the operability of catalyst systems, and improving catalyst productivity, as well as on designing new catalyst systems. Different catalyst manufacturing and catalyst preparation techniques have been used to try to improve the operability and productivity of catalyst systems.
One conventional technique for the preparation of supported catalyst systems is to slurry a solvent mixture of a catalyst component and activator with the support followed by heating to remove the solvent. Drawbacks to this technique can include product stability uncertainty as the time and temperature profile of the drying step may affect performance and productivity of the catalyst system. This uncertainty can escalate with metallocene catalyst components or other single-site components activated by aluminoxanes since some of these systems may be thermally unstable. In addition, extra care may be needed in handling these materials as the resulting catalyst systems may be air/moisture sensitive and/or pyrophoric.
Another method for preparing a supported catalyst system can involve contacting a supported activator with a catalyst component. While this method can result in a catalyst system with improved handling characteristics, the catalyst productivity may be less than optimal.
Thus, there is a continued need for improved methods for preparing and manufacturing catalyst systems. In particular there is a need for methods of preparing catalyst systems that result in improved catalyst systems having improved productivity and operability.